Christopher S Ogilvy

Beth Israel Deaconess Medical Center, Boston, Massachusetts, United States

Are you Christopher S Ogilvy?

Claim your profile

Publications (273)802.75 Total impact

  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: The preoperative evaluation of patients with intracranial aneurysms typically includes a contrast-enhanced vascular study, such as computed tomography angiography (CTA), magnetic resonance angiography (MRA), or digital subtraction angiography. However, there are numerous absolute and relative contraindications to the administration of imaging contrast agents, including pregnancy, severe contrast allergy, and renal insufficiency. Evaluation of patients with contrast contraindications thus presents a unique challenge. We identified three patients with absolute contrast contraindications who presented with intracranial aneurysms. One patient was pregnant, while the other two had previous severe anaphylactic reactions to iodinated contrast. Because of these contraindications to intravenous contrast, we performed non-contrast time-of-flight MRA with 3D reconstruction (TOF MRA with 3DR) with maximum intensity projections and volume renderings as part of the preoperative evaluation prior to successful open surgical clipping of the aneurysms. In the case of one paraclinoid aneurysm, a high-resolution non-contrast CT scan was also performed to assess the relationship of the aneurysm to the anterior clinoid process. TOF MRA with 3DR successfully identified the intracranial aneurysms and adequately depicted the surrounding microanatomy. Intraoperative findings were as predicted by the preoperative imaging studies. The aneurysms were successfully clip-obliterated, and the patients had uneventful post-operative courses. These cases demonstrate that non-contrast imaging is a viable modality to assess intracranial aneurysms as part of the surgical planning process in patients with contrast contraindications. TOF MRA with 3DR, in conjunction with high-resolution non-contrast CT when indicated, provides adequate visualization of the microanatomy of the aneurysm and surrounding structures.
    Journal of Clinical Neuroscience 05/2013; · 1.32 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: BACKGROUND AND PURPOSE: Many patients with aneurysmal subarachnoid hemorrhage (SAH) with intraparenchymal extension develop early hematoma expansion, which is not explained by aneurysmal rerupture in half of cases. In patients with primary intracerebral hemorrhage, the computed tomography angiography (CTA) spot sign predicts hematoma expansion and poor outcome. We conducted a 2-center prospective cohort study to evaluate whether CTA spot sign predicts case fatality in aneurysmal subarachnoid hemorrhage with intraparenchymal extension. METHODS: We studied consecutive patients with aneurysmal subarachnoid hemorrhage with intraparenchymal extension. Two experienced readers, blinded to clinical data, analyzed CTAs for spot sign presence. We assessed the proportion of patients with the CTA spot sign and tested its association with in-hospital and 90-day case fatality, using univariable and multivariable logistic regression. RESULTS: In 32 of 236 patients (14%), we found at least 1 spot sign. Acute surgical hematoma evacuation with aneurysm occlusion occurred in 120 patients (51%). The overall in-hospital case fatality rate was 37%. The CTA spot sign was not associated with in-hospital (multivariable odds ratio, 0.51 [95% confidence interval, 0.06-3.26]) or 90-day (multivariable odds ratio, 0.59 [0.21-1.65]) case fatality. CONCLUSIONS: The found frequency of CTA spot signs is lower after aneurysmal than primary intracerebral hemorrhage and is not associated with in-hospital or 90-day case fatality in patients with aneurysmal subarachnoid hemorrhage with intraparenchymal extension.
    Stroke 04/2013; · 6.02 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: The objective of this study is to assess the sensitivity of intracranial aneurysm geometry to the modality of imaging. Four imaging modalities—3D rotational angiography (3DRA), computed tomography angiography (CTA), contrast enhanced magnetic resonance angiography (CE-MRA), and time-of-flight magnetic resonance angiography (TOF-MRA)—were assessed using data from a flow phantom and human subjects. A silicone flow phantom of the head and neck arteries with a 10 mm ACOM aneurysm was imaged using all four modalities under steady flow conditions. Three human subjects with mid to large sized intracranial aneurysm who had a 3DRA scan and one of CTA, CE-MRA, or TOF-MRA performed within a day were also studied. The aneurysm and contiguous vasculature were segmented for all available scans and geometric measures of their size (5 indices) and shape (6 indices) were estimated and compared. Visually, the size and shape of segmented 3D models of the aneurysms were similar across scan modalities for both the human subjects and the flow phantom. Consequently, the computed indices were consistent across modalities in the key morphometric indices. In conclusion, quantified indices of 3D geometry of the mid to large sized intracranial aneurysms investigated in this small study population are not sensitive to scanning modality.
    Cardiovascular Engineering and Technology. 03/2013; 4(1).
  • Source
    Adam M H Young, Surya K Karri, Christopher S Ogilvy, Ninghui Zhao
    [Show abstract] [Hide abstract]
    ABSTRACT: Moyamoya disease is a slowly progressing steno-occlusive condition affecting the cerebrovasculature. Affecting the terminal internal carotid arteries (ICA) and there branches, bilaterally, a resulting in a fine vascular network in the base of the brain to allow for compensation of the stenosed vessels. While there is obvious evidence of the involvement of inflammatory proteins in the condition, this has historically not been acknowledged as a causal factor. Here we describe the fundamental histopathology, genetics, and signaling cascades involved in moyamoya and debate whether these factors can be linked as causal factor for the condition or whether they are simply a secondary result of the ischemia described in the condition. A particular focus has been placed on the multitude of signaling cascades linked to the condition as these are viewed as having the greatest therapeutic potential. As such we hope to draw some novel insight into potential diagnostic and therapeutic inflammatory targets in the condition.
    Frontiers in Neurology 01/2013; 4:105.
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Approximately 15% of patients with non-traumatic subarachnoid hemorrhage have no causative lesion identified on their initial angiogram. We present two patients with non-traumatic subarachnoid hemorrhage with negative initial angiograms that were subsequently found to have small basilar perforator aneurysms on delayed neurovascular imaging. We discuss the possible mechanisms for false negative diagnostic cerebral angiograms. These patients support the current standard of care with repeat angiography in cases of subarachnoid hemorrhage when no causative lesion can be identified on initial neurovascular imaging.
    Journal of Clinical Neuroscience 01/2013; · 1.32 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: : Electroencephalograms (EEGs) detect clamp-induced cerebral ischemia during carotid endarterectomy (CEA) and thus impact management and minimize the risk of perioperative stroke. We hypothesized that age, preoperative neurologic symptoms, ≥70% contralateral carotid and bilateral vertebral stenosis increase the probability of clamp-induced EEG changes, whereas ≥70% unilateral carotid stenosis does not. : This is an observational cohort study of 299 patients who underwent CEA with EEG monitoring at a single large urban academic medical center in 2009. Univariate and multivariate logistic regression were used. : Seventy percent or greater ipsilateral carotid stenosis decreases the odds of clamp-induced neurophysiologic dysfunction (odds ratio [OR] = 0.43, 95% confidence interval [CI] [0.18, 0.99], P = 0.04) after adjustment for symptomatic status, degree contralateral carotid or vertebral stenosis, and age. Preoperative neurologic symptoms, ≥70% contralateral carotid stenosis, and bilateral extracranial vertebral stenosis independently increase these odds (OR 2.62, 95% CI [1.32, 5.18], P = 0.005; OR 2.84, 95% CI [1.27, 6.34], P = 0.01; and OR 3.58, 95% CI [1.02, 12.53], P = 0.04, respectively), after adjustment for the other factors. Age ≥70 years has no significant impact. : Preoperative neurologic symptoms, ≥70% contralateral carotid, and bilateral vertebral stenosis increase the probability of clamp-induced ischemia as detected by intraoperative EEG, while ≥70% ipsilateral carotid stenosis decreases it.
    Journal of clinical neurophysiology: official publication of the American Electroencephalographic Society 10/2012; 29(5):462-7. · 1.47 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: BACKGROUND:: The Pipeline embolization device (PED) is the latest technology available for intracranial aneurysm treatment. OBJECTIVE:: To report early postmarket results with the PED. METHODS:: The study was a prospective registry of patients treated with PED at 7 American neurosurgical centers subsequent to FDA approval of this device. Data collected included clinical presentation, aneurysm characteristics, treatment details, and periprocedural events. Follow-up data included degree of aneurysm occlusion and delayed (>30 days postprocedure) complications. RESULTS:: Sixty-two PED procedures were performed to treat 58 aneurysms in 56 patients. Thirty-seven (64%) of the aneurysms treated were located from the cavernous to the superior hypophyseal artery segment of the internal carotid artery; 22% were distal to that segment, and 14% were in the vertebrobasilar system. 123 PEDs were deployed with an average of two implanted per aneurysm treated. Six devices were incompletely deployed; in these cases, rescue balloon angioplasty was required. Six periprocedural (during the procedure/within 30 days postprocedure) thromboembolic events occurred, of which five were in patients with vertebrobasilar aneurysms. There were four fatal postprocedure hemorrhages (from 2 giant basilar trunk and 2 large ophthalmic artery aneurysms). The major complication rate (permanent disability/death from perioperative/delayed complication) was 8.5%. Among 19 patients with 3-month follow-up angiography, 68% (13 patients) had complete aneurysm occlusion. Two patients presented with delayed flow-limiting in-stent stenosis that was successfully treated with angioplasty. CONCLUSION:: Unlike conventional coil embolization, aneurysm occlusion with PED is not immediate. Early complications include both thromboembolic and hemorrhagic events and appear to be significantly more frequent in association with treatment of vertebrobasilar aneurysms.
    Neurosurgery 08/2012; · 3.03 Impact Factor
  • Adam M H Young, Surya K Karri, Wanchun You, Christopher S Ogilvy
    [Show abstract] [Hide abstract]
    ABSTRACT: Non-steroidal anti-inflammatory drugs (NSAIDs) are among the most frequently prescribed therapies worldwide. Meta-analysis data indicate the potential for myocardial infarction, cerebrovascular incident, heart failure, renal failure and arterial hypertension. Here we review the mechanisms of their actions and the potential for therapeutic use in subarachnoid hemorrhage. Searches were performed using PubMed with the search terms "subarachnoid hemorrhage", "NSAID", "treatment", "management", "cerebral aneurysm", and "vasospasm" from 1970 to February, 2012. Articles were also identified through searches of the Cochrane library and searches of the authors' own files. Only papers published in English were reviewed.There are considerably mixed views on the potential impact of NSAIDs on the treatment and prevention of SAH. Whilst theoretically, the potential for positive intervention in the condition is huge, little effect appears to be measurable in clinical practice.
    Current drug safety. 08/2012;
  • Adam M H Young, Surya K Karri, Christopher S Ogilvy
    [Show abstract] [Hide abstract]
    ABSTRACT: The hypothesis that alterations in hormone levels can impact on subarachnoid hemorrhage (SAH) is rapidly gaining momentum. Specifically, the concept that post-menopausal women are more susceptible to the condition has convinced many of the protective roles of estrogen and progesterone. Here we review the mechanisms of their actions and the potential for estrogen and progesterone replacement therapy in subarachnoid hemorrhage. Searches were performed using PubMed with the search terms "subarachnoid hemorrhage", "estrogen", "progesterone "treatment", "management", "cerebral aneurysm", and "vasospasm" from 1970 to February, 2012. Articles were also identified through searches of the Cochrane library and searches of the authors' own files. Only papers published in English were reviewed. In conclusion, there is significant theoretical evidence for the potential role of estrogen and progesterone use in altering the pathogenesis of SAH. Nevertheless, this has received mixed reviews in both case controlled studies and cohort analysis within the literature.
    Current drug safety. 08/2012;
  • S K Karri, A M H Young, C S Ogilvy
    [Show abstract] [Hide abstract]
    ABSTRACT: The signal transduction of tumor necrosis factor-alpha (TNF-alpha) is complex and regulated via a vast number of interconnecting pathways. The TNF-alpha signaling pathway plays a major role in the pathogenesis of subarachnoid hemorrhage (SAH). The advent of molecular mimicry has provided a number of opportunities to tackle disease with improved specificity. Here we review the mechanisms of their action and the potential for TNF-alpha inhibitors as a treatment for subarachnoid hemorrhage. Searches were performed using PubMed with the search terms "subarachnoid haemorrhage", "TNF alpha", "novel drugs"TNF alpha inhibition", "management", "cerebral aneurysm", and "vasospasm" from 1970 to February, 2012. Articles were also identified through searches of the Cochrane library and searches of the authors' own files. Only papers published in English were reviewed. In conclusion, there is considerable theoretical evidence for the potential of TNF-alpha inhibitors to impact on the pathogenesis of aneurismal SAH. Such indications demonstrate the potential for specific targeting of molecular signaling pathways to prevent the growth and rupture of cerebral aneurysm.
    Current drug safety. 08/2012;
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Subarachnoid hemorrhage (SAH) is associated with inflammation that may mediate poor outcome in SAH. We hypothesize that elevated serum tumor necrosis factor α (TNF-α) and interleukin 6 (IL-6) are associated with vasospasm and poor outcome in SAH. In 52 consecutive SAH subjects, we compared TNF-α and IL-6 levels on post-SAH days 0 to 1, 2 to 3, 4 to 5, 6 to 8, and 10 to 14 with respect to vasospasm and to poor outcome at 3 and 6 months. Vasospasm was defined as more than 50% reduction in vessel caliber on angiography. Poor outcome was defined as modified Rankin score greater than 2. Elevated TNF-α on post-SAH days 2 to 3 was associated with poor 3-month outcome (P = 0.0004). Global elevation of TNF-α over time (post-SAH days 0-14) was independently associated with poor 3-month outcome after adjusting for Hunt-and-Hess grade and age (P = 0.02). Neither cross-sectional nor IL-6 levels over time were associated with outcome. Neither TNF-α nor IL-6 levels were associated with vasospasm. Elevation in serum TNF-α on post-SAH days 2 to 3 and global elevation of TNF-α over time are associated with poor outcome but not with angiographic vasospasm in this small cohort. Future studies are needed to define the role of TNF-α in SAH-related brain injury and its potential as a SAH outcome biomarker.
    Journal of Investigative Medicine 08/2012; 60(7):1054-8. · 1.50 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: : Numerous studies show that transient exposure to mild ischemia renders the brain resistant to a subsequent more severe ischemic stimulus, a concept known as preconditioning. Excitingly, this phenomenon has recently been demonstrated in subarachnoid hemorrhage (SAH), as mice transiently exposed to hypoxia developed an eNOS-mediated reduction vasospasm and neurological deficits following experimental SAH; however, this has never been studied in humans. In the present study, we hypothesize that patients with pre-existent steno-occlusive vascular disease experience ischemic preconditioning resulting in reduced SAH-induced cerebral vasospasm. : Retrospective case-controlled data from five high-volume SAH centers from 2006 to 2011 were pooled. Only Fisher 3 to 4 patients were included. The effect of pre-existent steno-occlusive vascular disease (extra- and intra-cranial atherosclerotic disease, and peripheral vascular disease) on the following endpoints was studied: angiographic vasospasm, symptomatic vasospasm, and stroke. Multivariate logistic regression analysis was performed with the following covariables; age, gender, Hunt-Hess grade, neurological deficit on admission, aneurysm location and type of aneurysm treatment. : A total of 771 patients were included, of which 198 (25.7%) had pre-existent vascular disease, 573 (74.3%) did not. Of those patients that had pre-existent vascular disease, 49 (24.7%) developed radiographic vasospasm, 30 (15.2%) symptomatic vasospasm and 26 delayed stroke (13.1%). Of those patients that did not have pre-existent vascular disease, 245 (42.8%) developed radiographic vasospasm, 131 (22.9%) symptomatic vasospasm, 84 (14.7%) delayed stroke. Multivariate logistic regression analysis demonstrated that older age and pre-existent vascular disease were significantly related with protection from radiographic and symptomatic vasospasm. Patients with pre-existent vascular disease had lower incidence of radiographic vasospasm (odds ratio, 0.524; 95% CI, 0.361-.0761; P = .001) and symptomatic vasospasm (odds ratio, 0.584; 95% CI, 0.385-0.885, P = 0.011). : These retrospective case-controlled data are the first evidence in human patients that ischemic preconditioning has an effect on reducing the incidence of angiographic and symptomatic vasospasm in patients with aneurysmal SAH.
    Neurosurgery 08/2012; 71(2):E553. · 3.03 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: Traumatic intracranial pseudoaneurysms in children are typically the result of blunt or penetrating head injury. There are isolated reports of pseudoaneurysm as the result of intracranial aneurysm surgery in both adults and children. Treatment of these lesions, both surgically and endovascularly, can be complicated due to the known variability of arterial wall thickness in traumatic pseudoaneurysms. We describe a child who underwent successful craniopharyngioma resection following staged surgical procedures. Follow-up imaging 8 months after the operation demonstrated an enlarging pseudoaneurysm of the left supraclinoid carotid artery. The lesion was successfully treated with stenting of the vessel and coil placement between the stent and the aneurysmal segment of the artery. Follow-up angiographic imaging 6 months later revealed complete obliteration of the aneurysm and normalization of the carotid artery lumen. To our knowledge, this is the first report of a pseudoaneurysm secondary to a surgical intervention in childhood that was treated with stent-assisted coiling. This strategy of vascular reconstruction is increasingly used in adults and appears safe to implement in the pediatric population. However, the long-term outcomes and the value of using an antiplatelet regimen in this young population are still to be determined.
    Pediatric Neurosurgery 07/2012; 47(6):442-8. · 0.50 Impact Factor
  • Surya Karri, Christopher S Ogilvy
    Current drug safety. 07/2012; 7(3):189.
  • [Show abstract] [Hide abstract]
    ABSTRACT: Recurrence after endovascular coiling of intracranial aneurysms is reported in up to 42% of cases and is attributed to the lack of endothelialization across the neck. In this study the authors used a novel tissue engineering approach to promote endothelialization by seeding endothelial progenitor cells (EPCs) within a fibrin polymer injected endovascularly into the aneurysm. Experimental aneurysms were created in New Zealand White rabbits and were left untreated, surgically clipped, or embolized with platinum coils, fibrin biopolymer alone, or fibrin combined with autologous cultured EPCs. In aneurysms treated with EPCs, a confluent monolayer of endothelial cells with underlying neointima was demonstrated across the neck at 16 weeks posttreatment, which was not observed with aneurysms treated using the other methods. This novel technique may address reasons for the limited durability of standard coil embolization and provides further avenues for the development of improved devices for the care of patients with aneurysms.
    Journal of Neurosurgery 06/2012; 117(3):546-54. · 3.15 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: Most intracranial aneurysms (IA) that present unruptured at the clinic remain stable over time with no measurable change or symptoms, if left untreated. But a few do grow larger and occasionally rupture. The ability to preemptively identify aneurysms that will become unstable over time (i.e., those that will grow and/or rupture) can result in timely intervention for these few patients while avoiding unnecessary treatment for countless others [1]. Previous reports assessing potential factors including by our group [2–4] have been confined to comparing geometric and/or biomechanical indices of aneurysms between populations that presented with ruputred lesions from those that presented with unruptured lesions. But, such indices (that discriminate rupture ‘status’) need not necessarily distinguish unruptured aneurysms that fork toward growth and/or rupture over a period of time from those that remain stable over time. Further, the physician’s dilemma to treat or not to treat presents itself mostly only in small aneurysms (< 7mm).
    ASME 2012 Summer Bioengineering Conference; 06/2012
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: The aim of this guideline is to present current and comprehensive recommendations for the diagnosis and treatment of aneurysmal subarachnoid hemorrhage (aSAH). A formal literature search of MEDLINE (November 1, 2006, through May 1, 2010) was performed. Data were synthesized with the use of evidence tables. Writing group members met by teleconference to discuss data-derived recommendations. The American Heart Association Stroke Council's Levels of Evidence grading algorithm was used to grade each recommendation. The guideline draft was reviewed by 7 expert peer reviewers and by the members of the Stroke Council Leadership and Manuscript Oversight Committees. It is intended that this guideline be fully updated every 3 years. Evidence-based guidelines are presented for the care of patients presenting with aSAH. The focus of the guideline was subdivided into incidence, risk factors, prevention, natural history and outcome, diagnosis, prevention of rebleeding, surgical and endovascular repair of ruptured aneurysms, systems of care, anesthetic management during repair, management of vasospasm and delayed cerebral ischemia, management of hydrocephalus, management of seizures, and management of medical complications. aSAH is a serious medical condition in which outcome can be dramatically impacted by early, aggressive, expert care. The guidelines offer a framework for goal-directed treatment of the patient with aSAH.
    Stroke 05/2012; 43(6):1711-37. · 6.02 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: PURPOSE: To evaluate the efficacy of n-butyl-2-cyanoacrylate (Trufill n-BCA) versus ethylene vinyl alcohol copolymer (ONYX) for the embolization of cranial dural arteriovenous fistulas (DAVF). METHODS: Fifty-three consecutive patients with cranial dural AVF were treated with liquid embolic agents from November, 2003 to November, 2008. These 53 patients had 56 lesions treated with arterial embolization. Patients embolized to completion underwent follow-up angiography at 3 months to assess for durable occlusion. RESULTS: Twenty-one lesions were treated with n-BCA. Seven patients treated with n-BCA had initial angiographic occlusion of their DAVF, which were durable at 3 months. Six patients had adjunctive treatment with coils and/or polyvinyl alcohol particles, but none of these were occluded by endovascular treatment alone. Eleven patients underwent post-embolization surgery for closure of their DAVF. There was one death related to intractable status epilepticus at presentation. One patient developed a major stroke from venous sinus thrombosis after embolization. Thirty-five lesions were treated with ONYX in 34 patients. Twenty-nine patients treated with ONYX had initial angiographic occlusion of their DAVF by embolization alone. One patient had recurrence at 3 months and was re-treated out of 27 total follow-ups. Four patients underwent post-embolization surgical obliteration of their lesions. No deaths or major strokes occurred in this cohort. CONCLUSION: Initial angiographic occlusion (p=0.0004) and durable angiographic occlusion (p=0.0018) rates for embolization of cranial DAVF show a statistically significant higher efficacy with ONYX compared with n-BCA. Patients embolized with ONYX underwent surgery less frequently compared with those treated with n-BCA (p=0.0015).
    Journal of Neurointerventional Surgery 05/2012; · 2.50 Impact Factor
  • David H Jho, Christopher S Ogilvy
    Journal of Neurointerventional Surgery 03/2012; · 2.50 Impact Factor
  • John C Barr, Christopher S Ogilvy
    [Show abstract] [Hide abstract]
    ABSTRACT: This article provides management guidelines for arteriovenous malformations (AVMs). Management options include observation, surgical excision, endovascular embolization, and radiosurgery. Each of these can be used individually or combined for multimodal therapy based on the characteristics of the lesion. The article stratifies each lesion based on the AVM and patient characteristics to either observation or a single or multimodal treatment arm. The treatment of an AVM must be carefully weighed in each patient because of the risk of neurologic injury in functional areas of the brain and weighed against the natural history of hemorrhage.
    Neurosurgery clinics of North America 01/2012; 23(1):63-75. · 1.73 Impact Factor

Publication Stats

6k Citations
802.75 Total Impact Points

Institutions

  • 2008–2015
    • Beth Israel Deaconess Medical Center
      • • Division of Neurosurgery
      • • Department of Emergency Medicine
      Boston, Massachusetts, United States
  • 1996–2015
    • Harvard Medical School
      • Department of Neurology
      Boston, Massachusetts, United States
    • University of Massachusetts Boston
      Boston, Massachusetts, United States
  • 1988–2014
    • Massachusetts General Hospital
      • • Department of Neurosurgery
      • • Department of Radiology
      • • Department of Neurology
      • • Neurology of Vision Lab
      Boston, Massachusetts, United States
  • 2013
    • University of Cambridge
      • School of Clinical Medicine
      Cambridge, ENG, United Kingdom
    • Thomas Jefferson University
      • Department of Neurological Surgery
      Philadelphia, Pennsylvania, United States
  • 2012
    • Mass General Hospital
      Boston, Massachusetts, United States
    • Partners HealthCare
      Boston, Massachusetts, United States
  • 2011
    • University of Pennsylvania
      Philadelphia, Pennsylvania, United States
    • Maria Sklodowska Curie Memorial Cancer Centre
      Gleiwitz, Silesian Voivodeship, Poland
  • 2010–2011
    • University at Buffalo, The State University of New York
      • Department of Neurosurgery
      Buffalo, NY, United States
    • State University of New York
      New York City, New York, United States
  • 2009
    • State University of New York College at Buffalo
      Buffalo, New York, United States
  • 2007
    • Centre hospitalier de l'Université de Montréal (CHUM)
      Montréal, Quebec, Canada
  • 2006
    • University of Southern California
      • Department of Neurological Surgery
      Los Angeles, CA, United States
  • 1996–2003
    • University of California, San Francisco
      • Department of Neurological Surgery
      San Francisco, CA, United States
  • 1990–2003
    • Beverly Hospital, Boston MA
      Beverly, Massachusetts, United States
  • 1998
    • Washington University in St. Louis
      San Luis, Missouri, United States